Wheel indexing mechanism

ABSTRACT

A printer having a plurality of decades each having a pivotal verge and print and readout wheels adapted to be simultaneously indexed by the verge. An eccentric rotatably mounted on the verge engages a power roll for oscillating the verge for indexing the wheels, and an electromagnet having an armature for latching the verge and eccentric is operable for releasing the latch for indexing the wheels.

United States Patent Hoffman 51 Aug. 1,1972

[54] WHEEL INDEXING MECHANISM [72] Inventor: Ernest G. Hoffman, Middlefield,

Conn.

[73] Assignee: Veeder Industries llnc., Hartford,

Conn.

[22] Filed: Sept. 8, 1970 [2]] Appl. No.: 70,343

[52] US. Cl. ..74/125, 235/1 C, 235/91 A, 235/92 F, 235/92 G [51] Int. Cl ..F16h 29/02 [58] Field of Search ..74/822, 2, 125, 125.5, 118,

74/116, 112, 84; 235/l.3, 91.1, 92 F, 92 G,

[56] v References Cited I UNITED STATES PATENTS 3,191,448 6/1965 Murphy ..74/577 X 3,448,639 6/1969 Adler ..74/822 Primary Examiner-William F. ODea Assistant Examiner-F. D. Shoemaker Attorney-Prutzman, Hayes, Kalb & Chilton 57 ABSTRACT A printer having a plurality of decades each having a pivotal verge and print and readout wheels adapted to be simultaneously indexed by the verge. An eccentric rotatably mounted on the verge engages a power roll for oscillating the verge for indexing the wheels, and an electromagnet having an armature for latching the verge and eccentric is operable for releasing the latch for indexing the wheels.

13 Claims, 1 Drawing Figure PATENTEDAUE 1 I972 INVENTOR ERNEST G. HOFFMAN BY/ZMW4' ya, M/ 1/ ATTORNEYS WHEEL INDEXING MECHANISM BRIEF SUMMARY OF THE INVENTION The present invention relates generally to wheel indexing mechanisms and more particularly to a wheel indexing mechanism of the type having a power rotor providing a source of indexing power.

It is a principal aim of the present invention to provide a new and improved wheel indexing mechanism for indexing a character wheel of a printer, counter or the like.

It is another aim of the present invention to provide a new and improved electromagnetically operated wheel indexing mechanism having an electromagnetic operator selectively operable for selectively indexing the wheel.

It is a further aim of the present invention to provide a printer having a new and improved electromagnetically operated print wheel indexing mechanism.

It is another aim of the present invention to provide a new and improved register having a plurality of wheels of increasing order and having individual wheel indexing mechanisms providing for either parallel entry for independently indexing the wheels or for serial entry for indexing the wheels for counting.

Other objects will be in part obvious and in part pointed out more in detail hereinafter.

A better understanding of the invention will be obtained from the following detailed description and the accompanying drawing of an illustrative application of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

The FIGURE is a side elevation view, partly broken away and partly in section, of a printer incorporating an embodiment of a .wheel indexing mechanism of the present invention.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail wherein like parts are designated by like numerals, a printer incorporating an embodiment of a wheel indexing mechanism of the present invention comprises a power rotor or roll 12 which is driven at a substantially constant speed (e.g., 700 RPM) by a suitable electric motor (not shown). The printer 10 comprises a stack of substantially identical sections or decades 14 (only one of which is shown in the Figure) and each decade 14 comprises print and readout wheels l6, 18 mounted in laterally spaced relationship in the same plane and a single pivotally reciprocable verge or drive arm 20 for indexing the wheels 16, 18 together. More particularly, each of the wheels l6, 18 has ten equiangularly spaced (i.e., angularly spaced 36) generally teardrop shaped pins or ratchet teeth 22 and the verge 20 has two pairs of opposed detent pawls 24, 25 and 26, 27 for indexing the wheels 16, 18 in unison. Thus, when the verge 20 is pivoted in the clockwise direction as viewed in the Figure, the pawls 24, 26 are withdrawn from between adjacent pins 22, and the opposed pawls 25, 27 are pivoted into engagement with the pins 22 to index the wheels one step or 18, in the counterclockwise direction as viewed in the Figure. When the verge is pivoted in the opposite pivotal direction, the pawls 25, 27 are withdrawn and the pawls 24, 26 are pivoted into engagement with the pins 22 to also index the wheels 16, 18 one step or 18, in the counterclockwise direction as viewed in the Figure. Pivotal overtravel of the verge in both pivotal directions is provided by the receipt of the active pawls between adjacent wheel pins 22 and such that the verge provides for locking the wheels 16, 18 against rotation between steps. Accordingly, by pivotally reciprocating the verge 20 back and forth the wheels l6, 18 are adapted to be indexed in unison in 18 steps and be locked against rotation between steps.

The print and readout wheels l6, 18 have 20 corresponding type and readout characters respectively such that the readout wheel 18 provides a visual readout of the type character at a printing station 32 where the type is operable to provide a printout on suitable paper 34 by operation of a print hammer 35. The twenty character print wheels l6, l8 bear for example two sequences of characters of 0-9 or bear one sequence of characters of 0-9 and any 10 additional characters including for example any desired letters and mathematical symbols.

The pivotal operation of the verge 20 is controlled by an electromagnetically operated control mechanism 40 having an electromagnet 42 and a pivotal armature 44. The armature 44 functions as a latch and normally remains in an outer pivotal position with its shoulder 47 in engagement with one of the angularly spaced verge shoulders 48, 49 (which are preferably at the same radial distance from the verge axis) to latch the verge from being pivoted, in the clockwise direction as viewed in the Figure, by a drive tension spring 52. The electromagnet 42 when energized attracts the armature 44 (against the bias of an armature return spring 53) to an inner pivotal position shown in part in broken lines in the Figure to disengage the verge 20 for pivotal operation by the drive spring 52.

A circular cam or eccentric rotor 54 is rotatably mounted on the verge 20 for engagement with the power roll 12. The cam 54 is preferably made of plastic and is suitably knurled and the power roll 12 has an outer hard rubber layer 55 to provide an appropriate friction drive between the power roll 12 and cam 54. The cam 54 is thereby adapted to be rotated by the power roll 12 for pivoting the verge 20, and the eccentricity of the cam 54 is established so as to pivot the verge 20 though the desired angle.

The cam 54 has a pair of integral abutments 60, 62 and the armature 44 has a second shoulder 68 engageable with the stops 60, 62 for latching the cam 54 against rotation by the power roll 12. The inner verge shoulder 48 is preferably located to engage the latch shoulder 47 after a few degrees of pivotal movement of the verge 20 (in the clockwise direction as viewed in the Figure) from its outer or counterclockwise pivotal end position, and the outer verge shoulder 49 is preferably located to engage the latch shoulder 47 a few degrees of pivotal movement of the verge before it reaches its inner or clockwise pivotal end position and such that in both in stances the verge 20 is near its respective pivotal end position and is moving relatively slowly toward the power roll 12 when the verge is latched. Also the abutments 60, 62 are preferably located to permit a few degrees of rotation of the cam 54 after the verge 20 is latched by the latch shoulder 47 and so that the cam 54 is free to be rotated by the drive roll 12 and (until the active abutment 60, 62 engages the latch shoulder 68) by the force of its rotational inertia and weight (due to the location of the center of gravity of the cam 54 as shown in the Figure) to lift the cam 54 out of engagement with the drive roll 12. The cam 54 is preferably lifted just enough to adequately disengage the cam 54 from the power roll 12. Also the latch shoulder 68 is located so that any shock resulting from the engagement of the rotating cam 54 with the latch shoulder 68 is absorbed by the verge return spring 52, and the center of gravity of the cam 54 is located for gravitationally holding the active abutment 60, 62 in engagement with the latch shoulder 68 and for therefore maintaining the cam 54 out of contact with the drive roll 12. When the electromagnet 42 is momentarily energized, the armature 44 is attracted against the bias of the tension spring 53 to momentarily withdraw the latch shoulders 47,. 68 to release the verge 20 for being pivoted by the cooperative action of the cam 54, power roll 12 and spring 52 to index the wheels 16, 18 one step. Also, since the verge 20 is operated back and forth at a continually changing angular velocity in accordance with a sine wave velocity curve and since the verge, is latched near its pivotal end or zero velocity positions, the verge is gradually angularly accelerated y from its rest position when the verge 20 is released.

Each momentary operation of the electromagnet 42 will therefore provide for momentarily unlatching the verge 20 for indexing the wheels 16, 18 an 18 increment and continuous operation of the electromagnet will provide for continuously indexing the wheels 16, 18 until the electromagnet is deenergized to release the armature 44.

A paper indexing mechanism similar to the described character wheel indexing mechanism is provided for indexing the paper 34 from a roll 80. The paper 34 is received between a pair of pressure rolls 82, 84 and a ratchet wheel 86 provided on the pressure roll 82 is engageable by a ratchet pawl 90 for indexing the paper. The ratchet pawl 90 is pivotally mounted on a spring biased bell crank 92 (which corresponds to the verge 20) and an eccentric or cam 96 is mounted on the bell crank 92 for engagement with the power roll 12 in the manner of the eccentric 54. An electromagnet (not shown) like the electromagnet 42 is provided for latching the bell crank 92 and cam 96 in the manner of the armature latch 44, excepting that the cam 96 has a single abutment 60 for latching the cam 96 and the bell crank 92 has a single cooperating shoulder 48 engageable by the armature latch. Thus, when the paper indexing electromagnet (not shown) is energized, its armature is attracted to release the bell crank 92 to provide for oscillating the pawl 90 through one full oscillation for indexing the pressure roll 82.

A printed circuit board 100 having 10 equiangularly spaced (i.e., angularly spaced 36) readout pads 102 associated with each character wheel l6, 18 is provided for producing electrical signals corresponding to the 20 character positions of the wheels. A two contact contact arm 106 is mounted on each of the wheels 16, 18 for selectively engaging the respective readout pads 102 and a common pad 107, and the contact arms 106 are angularly positioned on the wheels 16, 18 such thatwith the wheels in each full character position the outer contact 108 of one of the arms 106 engages a readout pad 102 and the outer contact 108 of the other contact arm 106 lies between readout pads 102. Preferably the contact arms 106 are located and the readout pads 102 are dimensioned to provide a makebefore-break circuit. f

The printed circuit board also includes a pair of diametrically opposed transfer pads 110 intermediate readout pads 102 associated with the readout wheel 18, and in a conventional manner the transfer pads 110 may be used where the printer is employed for counting and connected for energizing the electromagnet 42 of the adjacent higher order decade 14 (when the lower order decade is at 9") to index the wheels 16, 18 of the adjacent higher order decade one step for each 10 steps of the adjacent lower order decade (and as the lower order decade is indexed from 9 to 0). Where the ZO-character wheels 16, 18 are composed of only one sequence of characters of 0-9, the transfer pad 110 associated with the remaining characters would be left out of the transfer circuit, and the readout pads 102 associated with the remaining characters would be suitably connected so that each counter wheel would be automatically indexed ten steps through such remaining characters from 9 to 0.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

I claim:

1. In a multiple wheel register having a plurality of coaxial register wheels and a wheel indexing mechanism for each of the register wheels comprising a pivotal stepping member pivotal for indexing the wheel in stepwise fashion, operating means operable for pivoting the stepping member for indexing the wheel and control means for selectively operating the operating means for selectively indexing the wheel, the im provement wherein the register comprises an elongated power roll rotatable about an axis generally parallel to the axis of the coaxial register wheels, wherein the wheel indexing mechanism comprises a cam rotatably mounted on the respective stepping member for engagernent with the power roll for being rotated thereby for pivoting the stepping member, spring means biasing the stepping member in one pivotal direction for biasing the cam into engagement with the power,roll, and wherein the control means comprises an electromagnetic operator having an armature operative to latch the respective stepping member in at least one pivotal position thereof.

2. In a multiple wheel register according to claim 1 wherein the armature is operative for latching the cam against rotation by the power roll in cooperation with latching the stepping member. 9

3. In a multiple wheel register according to claim 1 wherein the armature is operative to latch the pivotal stepping member against the bias of the spring means as the stepping member is moving toward the power roll.

4. In a multiple wheel register according to claim 3 wherein the armature is operative to latch the pivotal stepping member against the bias of the spring means at each of two pivotal positions of the stepping member as it is moving toward the power roll.

5. In a multiple wheel register having a plurality of coaxial wheels, a wheel indexing mechanism for each of the wheels comprising a stepping member connected to be reciprocated back and forth for indexing the wheel in stepwise fashion, operating means operable for reciprocating the stepping member back and forth for indexing the wheel and control means for selectively operating the operating means for selectively indexing the wheel, the improvement wherein the register comprises an elongated power roll rotatable about an axis generally parallel to the axis of the coaxial wheels and wherein each wheel indexing mechanism comprises a cam rotatably mounted on the respective stepping member for engagement with the power roll for being rotated thereby for reciprocating the stepping member back and forth for indexing the wheel.

6. In a multiple wheel register according to claim 5 wherein the cam is circular and is eccentrically mounted on the stepping member.

7. In a multiple wheel register according to claim 5 wherein the control means comprises releasable latching means for latching the cam against rotation by the power roll.

8. In a multiple wheel register according to claim 7 wherein the releasable latching means is operable for latching the cam against rotation by the power roll at each of two angularly spaced positions of the cam.

9. In a multiple wheel register according to claim 7 wherein the releasable latching means provides for latching the stepping member against movement in at least one direction in cooperation with latching the cam against rotation by the power roll.

10. In a multiple wheel register according to claim 5 wherein the operating means comprises spring means biasing the stepping member in one direction for biasing the cam into engagement with the power roll.

11. In a multiple wheel register according to claim 5 wherein the control means comprises releasable latching means operable for latching the stepping member against movement in at least one direction.

12. In a multiple wheel register according to claim 11 wherein the releasable latching means comprises a pivotal latch having a first pivotal position for latching the stepping member and an electromagnetic operator for pivoting the latch from its said first pivotal position for releasing the stepping member.

13. In a multiple wheel register according to claim 5 wherein each wheel has an annular arrangement of spaced detent pins and wherein the corresponding stepping member is pivotally mounted for pivotal reciprocable movement and comprises a pair of generally opposed pawls engageable with the wheel pins for indexing the wheel in stepwise fashion and insertable between the pins to provide for pivotal overtravel of the stepping member. 

1. In a multiple wheel register having a plurality of coaxial register wheels and a wheel indexing mechanism for each of the register wheels comprising a pivotal stepping member pivotal for indexing the wheel in stepwise fashion, operating means operable for pivoting the stepping member for indexing the wheel and control means for selectively operating the operating means for selectively indexing the wheel, the improvement wherein the register comprises an elongated power roll rotatable about an axis generally parallel to the axis of the coaxial register wheels, wherein the wheel indexing mechanism comprises a cam rotatably mounted on the respective stepping member for engagement with the power roll for being rotated thereby for pivoting the stepping member, spring means biasing the stepping member in one pivotal direction for biasing the cam into engagement with the power roll, and wherein the control means comprises an electromagnetic operator having an armature operative to latch the respective stepping member in at least one pivotal position thereof.
 2. In a multiple wheel register according to claim 1 wherein the armature is operative for latching the cam against rotation by the power roll in cooperation with latching the stepping member.
 3. In a multiple wheel register according to claim 1 wherein the armature is operative to latch the pivotal stepping member against the bias of the spring means as the stepping member is moving toward the power roll.
 4. In a multiple wheel register according to claim 3 wherein the armature is operative to latch the pivotal stepping member against the bias of the spring means at each of two pivotal positions of the stepping member as it is moving toward the power roll.
 5. In a multiple wheel register having a plurality of coaxial wheels, a wheel indexing mechanism for each of the wheels comprising a stepping member connected to be reciprocated back and forth for indexing the wheel in stepwise fashion, operating means operable for reciprocating the stepping member back and forth for indexing the wheel and control means for selectively operating the operating means for selectively indexing the wheel, the improvement wherein the register comprises an elongated power roll rotatable about an axis generally parallel to the axis of the coaxial wheels and wherein each wheel indexing mechanism comprises a cam rotatably mounted on the respective stepping member for engagement with the power roll for being rotated thereby for reciprocating the stepping member back and forth for indexing the wheel.
 6. In a multiple wheel register according to claim 5 wherein the cam is circular and is eccentrically mounted on the stepping member.
 7. In a multiple wheel register according to claim 5 wherein the control means comprises releasable latching means for latching the cam against rotation by the power roll.
 8. In a multiple wheel register according to claim 7 wherein the releasable latching means is operable for latching the cam against rotation by the power roll at each of two angularly spaced positions of the cam.
 9. In a multiple wheel register according to claim 7 wherein the releasable latching means provides for latching the stepping member against movement in at least one direction in cooperation with latching the cam against rotation by the power roll.
 10. In a multiple wheel register according to claim 5 wherein the operating means comprises spring means biasing the stepping member in one direction for biasing the cam into engagement with the power roll.
 11. In a multiple wheel register according to claim 5 wherein the control means comprises releasable latching means operable for latching the stepping member against movement in at least one direction.
 12. In a multiple wheel register according to claim 11 wherein the releasable latching means comprises a pivotal latch having a first pivotal position for latching the stepping member and an electromagnetic operator for pivoting the latch from its said first pivotal position for releasing the stepping member.
 13. In a multiple wheel register according to claim 5 wherein each wheel has an annular arrangement of spaced detent pins and wherein the corresponding stepping member is pivotally mounted for pivotal reciprocable movement and comprises a pair of generally opposed pawls engageable with the wheel pins for indexing the wheel in stepwise fashion and insertable between the pins to provide for pivotal overtravel of the stepping member. 